Note: Descriptions are shown in the official language in which they were submitted.
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TAMPER-EVIDENT CLOSURE
This invention relates to closures for
containers and, more specifically, to a closure having a
tamper-evident assembly including abutment tabs on a band connected to the cap by breakable bridges.
Background ~f the Invention
Various designs of tamper-evident closures are
known which provide an indication that a container has
been opened. Such closures typically have a frangible
band assembly which breaks away from the cap (to which
it is connected by a number of thin frangible bridges)
and remains on the container finish upon the first
opening of the container. Certain closures include a
large number of tabs extending upwardly and inwardly
from the base of the band and abut a large annular
shoulder projection or breaker ledge on the container
finish beneath the screw thread to cause separation of
the tamper-evident band assembly upon th~e f~irtt opening
of the container. Such closures work ~ ~ with
relatively narrow-mouth closures~ However, with
closures of greater diameter, it is easier for tabs to
invert if the tabs are substantially longer and more
flexible. This results in the possibility that tabs on
adjacent closures might interlock in a hopper or
shîpping carton and invert with the tabs projecting
outwardly and downwardly rather than upwardly and
inwardly. While this inversion possibility is small,
complete user satisfaction is always desired. For
further information concerning the structure and
operation of such closures, reference mày be made to
commonly-assigned U.S. Patent Nos. 4~511,054 and
4,598,833.
Closures have been proposed which include 4n
annular inwardly folded ring which extends upwardly and
inwardly from the tamper-evident band for abutting the
finish breaker ledge. However t when compared with the
easily deflectable tabs, the requirement to stretch a
full ring results in the need to apply excessive force
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to install the closure. For large diameter glass
containers, e.g., about 3 inches or more in finish
diameter, the glass tolerance may be~ e.g., plus 0.012
and minus 0.013 inch. When the annular ring on the cap
is at a minimum diameter and the glass breaker ledge is
at a maximum tolerance diameter, the caps are often
damaged when the full annular ring is forced over the
breaker ledge. Another disadvantage of the need for
increased installation force is the chance of
prematurely damaging the bridges. For further
information regarding the structure and operation of
such closures, reference may be made to U.S. Patent Nos.
4,613,052 and 4,653,657.
Summary of the Invention
Among the several aspects and features of the
present invention may be noted the provision of an
improved tamper-evident closure. The closure of the
present invention has relatively low installation force
and reduces the possibility of tab inversion and
interlocking even when ~anufactured in wide diameter
sizes. Furthermorej the frangible bridges are protected
from premature rupture during installation of the cap.
Additionally, the closure of the present invention is
reliable ~n use with glass containers of large sizes
having considerable variations in diameter and is easy
and economical to manufacture. Other aspects and
features of the present invention will be, in part,
apparent and, in part, pointed out hereinafter in the
following specification and accompanying drawings.
Briefly, a closure embodying various aspects of
the prese~t invention is of one-piece molded
construction and includes a cap including a top wall
e~tending across the opening of the finish and an
annular skirt dependent ~rom the top wall with the top
wall and skirt being substantially coaxial and with the
skirt having an internal thread. The closure further
includes a tamper-indicating assembly made up of a band
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positioned below and spaced from the skirt with a
plurality of spaced ~rangible bridges detachably
connecting the upper end of the ~and to the lower end of
the skirt~ ~ segmented ring is connected to the bottom
5 of the band and extends upwardly and inwardly therefrom
with the ring being made up of a number of segments,
adjacent ones of which are separated by a slot providing
more ~lexihility than a solid, annular flange in passing
over maximum tolerance diameters on containers~ The
assembly further includes a plurality of resilient tabs
connected to each segment and extending upwardly and
inwardly therefrom with distal tab ends engaging the
breaker ledge abutment surface upon attempted removal of
the closure after its installation on the finish. The
tabs are sufficiently resiliently outwardly deflectable
by the breaker ledge cam surface during installation of
the closure on the finish so that upon removal of an
installed closure, and, on the other hand, the tabs are
sufficiently stiff that the free ends of the tabs
bearing on the ledge will cause the bridges to break
resulting in an indication of tampering.
Brief Description of the Drawings
FIG. 1 is a side elevational view of a closure
embodying various feat~res of the present invention
installed on the finish of a container;
FIG. 2 is a cross-sectional view of the closure
of F~G. 1 in its as-molded condition showing a
tamper-evident assembly including a band and abutment
tabs extending from a segmented ring joined to the band;
FIG. 3, similar to FIG. 2, illustrates the
closure of FIG. 1 in its ready-for-installation
condition;
FIG. 4 is a fragmentary, sectional elevational
view of the closure o~ FIG. 1 shown in installed
relation upon a container finish, with certain
components shown in phantom in a fully deflected
posltion;
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FIG. 5 is ~ enlarged fragmentary front
elevational view of the closure in its as-molded
condition depicting tabs extending from a ring segment;
FIG. 6 is a sectional view of the closure taken
generally along line 6-6 of FIG. 3.
Corresponding reference numbers indicate
corresponding components throughout the several views of
the drawings.
Description of the Preferred Embodlment
Referring to the drawings, a tamper-evident
closure embodying various aspects of the present
invention is generally indicated by reference numeral
20. The closure 20 is preferably of one-piece molded
thermoplastic construction with a preferred material
being polypropylene, and includes a cap 22 and a
tamper-evident assembly 24 joined to the cap by a number
of regularly spaced ~rangible bridges 26. Closure 20 is
useful for sealing an open-topped container 28, portions
of which are shown in FIGS. 1 and 4, including a neck or
finish 30 having an external screw thread 32 and an
annular projecting shoulder or breaker ledge 34 disposed
beneath the level of the thread 32. The ledge 34 is
provided with an upper cam surface 36 facing the thread
and a lower abutment surface 38 remote from the thread.
The tamper-evident assembly is, in essence, a one-way
device which cooperates with the cam surface to permit
relatively low force movement of the assembly beneath
the level of the ledge during installation of the
closure, but which cooperates with ledge abutment
surface to break the bridges when the cap is first
removed from the container.
More specifically, the cap 22 includes an
annular top wall 40 for extending across the opening of
the finish 30. An annular sidewall or skirt 42 is
dependent from the top wall 40 and is joined thereto
about the periphery of the top wall so that the top wall
and the skirt are substantially coaxial. The skirt 42
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has an internal screw thread 44 conEigured to cooperate
with the thread of the fil~ish to enable the cap 22 to be
installed on and removed from the container 28 by
screwing and unscrewing, respectively. The skirt 42 is
preferably provided with an internal retention rib
adjacent the top of the internal screw thread 44 for
retaining a disc of resiliently compressible material
which is compressed between the top wall 40 and the
open-end of the finish to seal the open end. The
exterior surface of the skirt preferably has a large
number of regularly spaced axially extending ribs to
enhance the user's grip on the cap. The
tamper-indicating assembly 24 is best shown in its
ready-for-application condition in FIGS. 3 and 6 and
comprises a band 46 of relatively thick cross section
connected to the outwardly flaring bottom of the skirt
by the thin bridges 26.
In accordance with the present invention, the
tamper-evident band has increased rigidity over the tabs
20 on the closure of U.S. Patent No. 4,511,054 because of a
segmented ring 48 and has greater flexibility for large
diameter tolerances than the full annular ring of U.S.
Patent No. 4,653,657 because of tabs 54 projecting from
the ring segments to engage the breaker ledge. The
segmented ring 48 is connected to the base of the ~and
and extends upwardly and inwardly therefrom. The ring
48 is made up by three to five segments 50, four being
pre~erable, with adjacent segments separated by a slot
52 extending substantially to the band. A plurality of
resilient tabs 54 is connected to the distal end of each
segment for engaging the abutment surface 38 of the
breaker ledge 34. There are preferably six to ten tabs
carried by each segment with eight per segment being
most preferable.
Referring to FIGS. 2 and 5, in the as-molded
condition of the closure, the ring and tabs extend
downwardly because this configuration permits
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simplification in the molding process and equipment.
Within a short time after molding the segment ring and
the tabs are reoriented by rolling or any other suitable
means, as well known by those o~ skill in the art, to
extend upwardly. Heat may be applied to destroy the
plastic memory at the hinge area, if desired. Thus, the
components will remain in ready-for-installation
position depicted in FIGS. 3 and 6.
As best shown in FIG. 4, the tabs increase in
thickness with distance from their connected ends and,
as shown in FIG. 5, have a slight decrease in width from
their connected ends. The segments 50 also increase in
thickness with distance from the band with the segments
and tabs having substantially equal thickness at their
juncture. The increase in thickness provides some
increase in stiffness but also aids in preventing the
tabs from being bent over the breaker ledge without
breaking the bridges. This is termed "tiring off" in
the manner that a tire is canted and inclined and peeled
about the tire rim.
Referring to FIG. 4, the internal diameter at
the base of the skirt and the internal diameter of the
band 46 are substantially equal. The tabs 54 have their
greatest thickness at their free ends to take up
tolerances and prevent tiring off of the tamper-evident
band with the cap during cap removal. As shown in
phantom in FIG. 4, installation of the closure 20 of the
finish 30 causes substantially full outward deflection
of the tabs 54 but does not result in substantial
deformation as would break the bridges 26.
Adjacent bridges 26 are spaced by abutment
blocks 58 which function to limit movement of the band
46 toward the bottom 56 of the skirt during installation
of the closure to protect against premature breakage of
the bridges. More specifically, the blocks 58, which
may be of rectangular cross section, extend from the top
surface 60 of the band 46 about halfway toward the
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bottom surface 62 of the skirt. The relatively thin
bridges, as shown in FIG. 4, are positioned at the
inside of the band whereas the relatively thick blocks
58 have the same thickness as the band and skir~ bottom
and are aligned therewith. Accordingly, the blocks have
much ~reater column strength than the bridges. During a
downward closure application, the thin bridges 26 may
buckle and permit the bottom surface of the skirt to
abut the top surface of the blocks 58 and prevent
further buckling of the bridges to the extent that the
bridges are damaged or broken.
The combination of the segmented ring 48 and
the tabs 54, which preferably have a somewhat greater
length than the ring, provides important advantages over
conventional closures particularly in sizes having large
diameters. Prior art connectors in which the numerous
tabs extend to the band can be inadvertently inverted
particularly in the wide diameter sizes. This can
result in the tabs of adjacent closures in a shipping
carton becoming entangled, requiring manual separation
of closures intended to be applied by automated
equipment. As shown in FIG. 6, each of the segments is
folded upwardly and inwardly when put into a feeding
hopper for an automatic capping machine. Because the
long arcuate ring segment is much stiffer than would be
a narrow long tab tif the ring segment were not used in
patent 4,511,054) the ring segment will not be
inadvertently inverted as it would, with its relatively
high stiffness, have to be pulled over center and then
to a reversely bowed configuration. Even if one of the
tabs were acted upon by a force trying to invert it or
its attached ring segment, the ring is sufficiently
stiff that it should not invert. Still the closure
provides acceptably low installation force because the
relatively flexible tabs can be easily deflected by the
downwardly sloping cam surface 36 of the breaker ledge
34. The segme~ted ring can also be deflected without
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excessive force because no full hoop kind of stretching
is required (as would be required for installation of a
full ring).
Operation of the closure 20 of the subject
invention is as follows: Upon placing the closure over
the open end of the container finish 30 and engaging the
cooperating screw threads 32 and 44, screwing of the
closure results in the segmented ring 48 engaging the
cam surface 36 of the breaker ledge 34. Continued
screwing of the closure onto the container causes the
cam surface to deflect the ring segments 50 and then
deflect the tabs 54 carried by the segments. As shown
in phantom in FIG. 4, when the tabs are fully deflected
they are disposed adjacent or against the inside
surfaces of the band 46, the bridges 26 and the lower
portion of the skirt 42. When the free ends of the tabs
54 pass the greatest diameter portion of the breaker
ledge, the tabs, due to their resiliency, will return
toward their undeflected position and engage the finish
exterior surface beneath the level of the breaker ledge
34.
It will be appreciated that during application
of the closure, the bridges may ~Indergo some slight
buckling or bowing as the cap 22 moves toward
tamper-evident assembly 24 due to the drag of the
segments 50 and/or tabs 54 on the breaker ledge. This
bowing is limited by the presence of the blocks 58 which
engage the bottom surface 62 of the skirt 42 to limit
movement of the band toward the skirt thereby protecting
the bridges from breakage or other premature damage
during closure installation.
Upon attempted unthreading of the cap, the free
ends of the tabs are brought into engagement with the
abutment surface 38 of the breaker ledge 34. Continued
unscrewing causes the tabs to more forcefully bear upon
this surface. The resistive strength of the tabs 54 is
greater than the rupture strength of the bridges 26 so
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that upon continued application of unscrewing forces the
bridges rupture allowing the cap to be removed, with the
tamper-evident assembly 24 remaining captured on the
finish beneath the level of the breaker ledge thereby
providing positive indication that the container has
been opened.
In view of the above, it will be seen that the
several objects of the invention are achieved and other
advantageous results attained.
As various changes could be made in the above
construction without departing from the scope of the
invention, it is intended that all matter contained in
the above description shall be interpreted as
illustrative and not in a limiting sense.
